This invention relates to improvements in a charge coupled semiconductor device and to a method of driving the improved device.
One well known example of charge coupled device (which is sometimes abbreviated hereinafter as "CCD") configuration shift registers includes a plurality of bit positions each formed by four transfer electrodes which stepwisely transfers binary information by means of four phase driving pulses applied in a predetermined sequence to the transfer electrodes. Since each bit position is formed by four transfer electrodes it can not be said that such a shift resister has a high degree of intergration. Also, since the quantity of electric charge which can be accumulated under each transfer electrode is proportional to the area of that electrode, an increase in the degree of intergration due to, for example, a decrease in electrode area or adoption of a multi-level accumulation of electric charge encounters problems because the output from such shift resisters has an insufficient sensitivity and a reduced signal-to-noise ratio.
Accordingly it is an object of the present invention to provide a new and improved charge coupled semiconductor device having an increased degree of integration.
It is another object of the present invention to provide a new and improved charge coupled semiconductor device having an increased data storage density with the configuration of the transfer electrodes remaining unchanged from the prior art practice and also to provide a method for driving such a device.
It is still another object of the present invention to provide a new and improved charge coupled semiconductor device capable of storing 2-bit information in each electrode unit forming one bit position.
It is an additional object of the present invention to provide a new and improved charge coupled semiconductor device with an increased quantity of transferable charge.